1. Field of the Invention
The present invention relates to a device for packaging and dispensing a product comprising several constituents which must be stored separately and mixed just before the product is used, with a view to its application to a suitable base. The invention relates more particularly for the storing, mixing and dispensing of a cosmetic or dermatological product obtained by mixing two, three, four or more constituents. Such a product is, for example, a hair dye, or a hair perm composition which usually takes the form of at least two constituents of which one contains, for example, oxidizing or reducing agents which must only come into contact with active agents (or colorants) of the other constituent of the product at the time of application, since in the medium term one of these constituents causes the other to be rendered inactive. A third or even a fourth constituent may contain respectively a perfume or a hair conditioning agent, a sun-protection agent, or a surfactant.
2. Description of the Related Art
From FR-A-1 542 467 there is known a packaging unit for a two constituent product, comprising first and second compartments for the two constituents, these compartments being placed on one another and assembled by means of an intermediate connecting element slidably mounted relative to each compartment and having an outlet duct. Opposite each end of the intermediate connecting element, a stopper obturates the outlet of each compartment. When it is intended to mix together the constituents contained in each compartment for applying the mixture obtained, the two compartments are brought together to eject the stoppers so as to open the outlet of the intermediate element and allow the two constituents to be mixed.
This packaging unit has two main drawbacks. On the one hand, it is difficult to ensure an adequate seal between the intermediate elements and each compartment, respectively, in that when this seal has not been ensured leaks of one or the other constituent towards the outside may occur. On the other hand, during the ejection of the stoppers a reduction of the total volume of the packaging unit is produced, which results in an increase in the internal pressure. It is therefore necessary to ensure a perfect seal between the sliding parts, which in practice is difficult to obtain on an industrial scale. Moreover, when the packaging unit of the prior art is opened after mixing, there is the risk that the excess pressure obtaining inside will produce splashes, which is very detrimental because corrosive constituents may be used in the intended fields of application.